Internal combustion engine



Feb. 24, 1942. B. NORDS TROM INTERNAL COMBUSTION ENGINE 3 Sheets Sheet 1 Filed March 6, 1940 Feb. 24, 1942. NORDSTROM 2,273,882

INTERNAL COMBUSTION ENGINE Filed March 6, 1940 s sheets-sheet 2 Feb. 24, 1942. B. A. NORDSTROM INTERNAL COMBUSTION ENGINE Filed March 6, 1940 s Sheets-Sheet s Patented Feb. 24, 1942 T OFFICE INTERNAL COMBUSTION ENGINE V Bror Arne Nordstrom, Trollhattan, Sweden ApplicationMarch s, 1940, Serial No. 322,524

' In Sweden February 2, 1939' 10 Claims.

The present. invention rel-ates to internal combustion engines of the typehaving a plurality of radially arranged. cylinders rotatable together with the. crank case about the axis of the crank shaft. ,In this type of engines it is well-known to control the admission of the driving fluid to the cylinders and the exhaust of the combustion products therefrom by means of a stationary ring surrounding the rotary. cylinder block To this end, said ring is provided with inlet and outlet channels opening into the inner peripheral surface of the ring in order during the rotation of the cylinder block to be brought into communication with the various cylinders at the proper moments through ports formed in the cylinder heads. 1 I

While passing between each. two adjacent cylinders the openings of said channels should be closed in order to prevent the driving fluid, as wellas the exhaust gases, from taking other ways than those aimed at. It is already known to effect this closure by means of arc-shaped slide shoes carried by the cylinders at the outer ends thereof which slide against the inner peripheral surface-of the stationary regulating ring during the rotation of the cylinder block. Said slide shoes while forming alltogether a circular row around the cylinder block, are individually movable radially to a little extent; thus during the operation of; the engine, they are pressed under the influence j of the centrifugal force with sufficient power against the stationary regulating ring to secure a reliable sealing effect.

"It is desirable, however, that the slide shoes be forced against the stationary ring also when the motor is started or stands still. It is an object of this invention to provide means whereby this'result may be obtained. Another object of the invention is to prevent leakage ofoil at the points where the slide shoes abut uponeach other, and still another object is to prevent the slide shoes from getting askew when in rotation. With these and other objects in view, one featuie ofthe invention involves that the slide shoes engage; each other at their abutting ends in suchia way as to form an oil seal and guide each other against transverse displacements, so that they c'annot take up a zigzag position, in case of an odd number of slide shoes.

In theaccompanying drawings one embodiment of theinvention is illustrated. I

Fig. "1 is a side elevation, partly in section, of aportion of a radial engine to which the invention has been applied.

Fig. 2 is an:end view, partly in cross section, of a portion of the engine shown in Fig. 1.

Fig. 2a is a view, 'on larger scale, of part of the structure shown in Fig. 2.

Fig. 3 is a perspective view of a pair of slide shoes in engagement with each other, as seen from the inside. v

Fig. 4 is a perspective view of a pair of slide shoes inengagement with each other as seen from the outside.

Figs. 5-7 are perspective views of three different embodiments of intermediateshoes adapted to be placed at the joints of the slide shoes.

Fig. 8 shows a development of the slide shoes of a ,7-cylinder radial engine.

In the drawings is shown as an example, a 7- cylincler radial engine, especially built for use asan aeroplane engine, I indicates the crank shaft and 2 the propeller shaft which is situated on a line with the crank shaft and is driven therefrom by the aid of a transmission gear (not shown) enclosed in the casing 3, Fig. 1. The casing 3 is rigidly connected to the crank case 4 of the engine and both casings are rotatable about the common axis of the shafts I and 2, the

crank case 4 being rotatably mounted in the frame 5 of the engine. The rotation of the crank case is derived from the gear inside the casing 3. The cylinders 6 are radially mounted in the crank case so as to rotate therewith. Ifhe rotatable block is surrounded by a stationary ring I rigidly connected to the frame 5 which serves to control the admission of the driving fluid to the cylinders and the exhaust of the combustion gases therefrom. To this end said ring is provided with inlet channels 8 and outlet channels 9 connected to admission and exhaust pipes, respectively, not shown. Said channels 8 and 9 open by way of suitable valve ports in the inner peripheral valve track surface of the ring 1 which serves as a guide surf-ace for the cylinder ring; The connection between said channels and the cylinders is effected by ports in the cylinder heads. Each cylinder carries at its outer end a slide shoe l0 bearing against the inner peripheral surface of the stationary ring I. The slide shoe act to close the openings of the channels 8 and 9 when, during the rotation of the cylinder block, said openings are right opposite the spaces between the cylinders, in order to prevent the driving fluid as well as the exhaust gases from taking other ways than those represented by the channels Band 9 and the connected pipes. Each slide shoe is of a peripheral length correresponding, substantially, to the angular distance between each two adjacent cylinders, so that the slide shoes all together constitute a circular row around the cylinder block.

The slide shoes are mounted on the cylinders so as to be capable of a slight radial movement with relation thereto. To this end each slide shoe has an opening H slidably engaged by the cylinder head. Due to this mounting the slide shoes, when in rotation, will be forced against the stationary ring I under the influence of the centrifugal force, thereby securing a tight sealing between the stationary ring I and the slide shoes I0. It is to be noted however, that a tight sealing between the slide shoes and the ring I is required also when there is no centrifugal force, that is to say, while the motor stands still, or when the centrifugal force is insufficient, as in starting. To this end the slide shoes are loaded by outwardly acting springs I2, preferably located at the points where the slide shoes abut upon each other, as shown in Fig. 2.

Figs. 3 and 7, in which no springs are shown, illustrate the arrangement of the slide shoes with relation to each other. At one end each shoe has a recess 13 bounded by lateral surfaces at right angles -to the shaft and a bottom surface situated in an axial plane. At its other end the shoe has a projection M of the same axial width as that of the recess, so that it can engage the recess of the adjacent slide shoe to be guided thereby. Owing to this engagement the slide shoes cannot get askew with relation to each other, when there is an odd number of them, as is usually the case in connection with four cycle engines, because such engines, as a rule, have an odd number of cylinders. This result will appear from Fig. 8, showing a development of the slide shoes of a 'l-cylinder radial engine. The zigzag line indicates one of the two conceivable zigzag positions of the slide shoes, and the arrows indicate the directions in which the ends of the zigzag line showntend to move. As, however, the bending of the row of slide shoes into the form of a circular ring will bring the free ends of the row into engagement with each other, the tendencies for the end shoes of getting askew will neutralize each other. Similar conditions prevail as far as the other zigzag position conceivable is concerned. It is thus seen that the individual shoes of the circular row of slide shoes will be positively prevented from getting askew with relation to each other without the aid of any separate guiding means. The slide shoes are such a length that in the assembled state of the slide shoes, slots 15, f6 are formed between the end surfaces 'of the projections 14 and the bottoms of the recesses 13 as well as between the shoulders on opposite sides of the projections l4 and the narrow projections H on opposite sides of the recesses it. Thus, said slots extend at right angles to the longitudinal direction of the slide shoes, that is to say axially, the opposite axial surfaces of the slots being approximately parallel. The slots, which are provided with a view to facilitate the mounting of the slide shoes and allow the expansion of the shoes due to heating, must be closed in the completely erected state of the engine, in order not to form passages by which gases or oil may escape. To this end, the slots 5-5, H5 are partly filled by projections i8 and 49, respectively, of joining pieces referred to as intermediate shoes in this description. These intermediate shoes are placed inside the circular row of slide shoes at the joints thereof so that the projections l8 engage the slots [5 and the projections I9 engage the slots 16. The projections are not only of the same length but also of the same height as the respective slots so that their top surfaces will be on a level with the outer peripheral surface of the slide shoes. The end portions of the slide shoes may be milled on their inner surface so as to present plane contact surfaces 2!, Fig. 3, to the intermediate shoes which in this case are of the shape shown in Fig. 5, that is to say, include a plane base plate. The intermediate shoes are forced against the slide shoes by means of springs I2 acting at the same time to keep the slide shoes in contact with the ring 1. Said springs 12 are supported by washers 22 on screws 23 which in their turn are carried by yokes 24 secured to projecting parts of the cylinders. The yokes 24 are of two-piece construction, the screws 23 being threaded through the yoke parts 24a and passing freely through the bores in the yoke parts 24b. Parts 2 1a and 25b are recessed at their ends to provide slots in which members 26 of suitable soft material such as rubber may be clamped when the parts of the yokes are clamped together, as by means of the nut and washer assembly indicated at 23a. .The relatively soft members 26 are engaged by enlarged cooling ribs 25, the yielding material operating to reduce wear between the parts and also to allow for minor inaccuracies in construction.

Each screw 23 engages a guideway provided on the respective intermediate shoe in such a way as to allow slight radial movements of the intermediate shoe and the slide shoes engaged thereby without the guideway striking a stop member 21 on the screw. The distance (which may be of the order 0.5 to 3 mm.) between the guideway and said stop member, however, should be so short that the slide shoes will return without fail to their proper position after having been forced radially inwards towards the stop member. The object of the stop member is to avoid trouble in the event of explosions in the exhaust channels 9, the abnormally high pressure resulting from such an explosion forcing the slides out momentarily till they are checked by the stop members.

The plate 20 with its projections forms in conjunction with the surface 2! and the slots l5, l5 a sort of labyrinth packing at the joints between the slide shoes which prevents leakage of oil. The slots It provided in the edges of the ring of slide shoes are closed to the atmosphere in every direction, so that the oil has no chance to escape to the sides through said slots.

Instead of the plane intermediate shoe shown in Fig. 5, a cylindrical shoe may be used, as shown in Fig. 6. In that case the contact surface 2| should also be cylindrical, preferably, concentric with the axis of rotation of the engine. This form of the intermediate shoe renders the manufacture more easy.

In Fig. '7 a spherical intermediate shoe is shown which is adapted to engage a spherical contact surface 2!. This form secures a good contact and a good sealing effect even if the slide shoes should move laterally due to a transverse play.

The mounting and dismantling of the intermediate shoes may be attended to without difliculty, as there is ample space to permit the insertion 0f the shoes radially from inside and the removal of them radially inwardly. When the intermediate shoes are removed, the slide shoes may be assembled to form an annular row of a diameter less than the normal one, because of the slots l5, 16. Thus, the slide shoes may move with the cylinders when the latter are inserted in the crank case to such an extent as to project with their inner ends beyond their normal definite position in order to allow the insertion of the cylinder block into the stationary, usually spherical ring I, or the removal of the cylinders therefrom.

It is to be noted that the invention may be applied to other kinds of engines than that above described and changed in respect of its details Without departing from its principle.

What I claim is:

1. An internal combustion engine having a retatably mounted block of radially arranged ported cylinders, a stationary valve ring encircling said cylinders and having a ported inner valve track surface, the ports in said valve track being successively brought into communication with the cylinder ports upon rotation of the cylinders,

and slide shoes carried by the cylinders for closing thevalve ports when they are not in communication with the cylinder ports, said shoes being interconnected to form a circular ring and having axially spaced sets of peripherally overlapping surfaces interengaging to prevent angular displacement of the shoes relative to each other and to the plane of rotation of the cylinders.

2. An internal combustion engine having a rotatably mounted block of radially arranged ported cylinders, a stationary valve ring encircling said cylinders and having a ported inner valve track surface, the ports in said valve track being successively brought into communication with the cylinder ports upon rotation of the cylinders, slide shoes carried by the cylinders for closing the valve ports when they are not in communication with the cylinder ports, said shoes being interconnected to form a circular ring and having co-engaging recesses and projections at their ends providing peripherally overlapping surfaces for guiding the shoes against angular lateral displacement, the peripheral length of the shoes being so related to the circumference of the ring formed thereby that in the operative position of the shoes slots are provided between adjacent shoes, whereby to permit easy mounting and dismantling of the shoes and intermediate shoes bearing against the inner surfaces of the slide shoes, said intermediate shoes having portions located in and partially closing said slots. f

3. A structure as set forth in claim 2 in which each intermediate shoe comprises a plate portion arranged to engage the adjacent radially inner end surfaces of adjacent slide shoes, and proengaging surfaces of said plate portion and said slide shoes being plane, and projections extending radially outwardly from said plate portion into said slots.

5. A structure as set forth in claim 2 in which each intermediate shoe comprises a plate portion arranged to engage the adjacent radially inner end surfaces of adjacent slide shoes, the engaging surfaces of said plate portion and said slide shoes being cylindrical and concentric with the axis of rotation of said cylinders, and projections extending radially outwardly from said plate portion into said slots.

6. A structure as set forth in claim 2 in which each intermediate shoe comprises a plate portion arranged to engage the adjacent radially inner end surfaces of adjacent slide shoes, said valve track being spherically curved and the engaging surfaces of the plate portions of said intermediate shoes and of said slide shoes being spherically curved about the same center as that of the valve track, and projections extending radially outwardly from said plate portion into said slots.

7. A structure as set forth in claim 2 having supporting means located in the spaces between the radial cylinders and attached to parts thereof and springs carried by said supporting means and bearing against said intermediate shoes.

8. A structure as set forth in claim 2 having supporting means located in the spaces between the radial cylinders and attached to. cooling ribs on said cylinders, and springs carried by said supporting means and bearing against said interjections extending radially outwardly from said plate portion into said slots.

4. A structure as set forth in claim 2 in which each intermediate shoe comprises a plate portion arranged to engage the adjacent radially inner end surfaces of adjacent slide shoes, the

mediate shoes.

9. A structure as set forth in claim 2 having supporting means located in the spaces between the radical cylinders and attached to parts thereof, and springs carried by said supporting means and bearing against said intermediate shoes, said supporting means including yieldable members of relatively soft material interposed in the path of force transmission between said springs and said cylinder parts.

10. In an internal combustion engine of the I kind having a rotatable bank of radially arranged ported cylinders and an encircling ported valve track cooperating with said ported cylinders, a ring of slide shoes carried by said cylinders and adapted to close the valve ports when they are not in communication with the cylinder ports, said slide shoes inter-engaging at their ends and having slots therebetween to permit expansion and contraction of the shoes in peripheral direction within said valve track, and intermediate shoes having portions engaging the ends of said slide shoes on their radially inner surfaces and having projections extending radially outwardly into and partially filling said slots, whereby to provide overlapping surfaces effecting a labyrinth type of oil seal at the joints between said slide shoes for preventing f leakage of oil from said valve track through said joints.

BROR- ARNE NORDSTROM. 

